TheWorld Ocean Circulation Experiment (WOCE) was a component of the internationalWorld Climate Research Program, and aimed to establish the role of theWorld Ocean in theEarth'sclimate system. WOCE's field phase ran between 1990 and 1998, and was followed by an analysis and modeling phase that ran until 2002.[1] When the WOCE was conceived, there were three main motivations for its creation. The first of these is the inadequate coverage of the World Ocean, specifically in theSouthern Hemisphere. Data was also much more sparse during the winter months than the summer months, and there was—and still is to some extent—a critical need for data covering all seasons. Secondly, the data that did exist was not initially collected for studying ocean circulation and was not well suited for model comparison. Lastly, there were concerns involving the accuracy and reliability of some measurements. The WOCE was meant to address these problems by providing new data collected in ways designed to "meet the needs of global circulation models forclimate prediction."[2]
1. Develop ocean models that can be used in climate models and collect the data necessary for testing themSpecifically, understand:
Large scale fluxes of heat and fresh water
Dynamical balance of World Ocean circulation
Components of ocean variability on months to years
The rates and nature of formation, ventilation and circulation of water masses that influence the climate system on time scales from ten to one hundred years[3]
In order to achieve Goal 1, the WCRP outlined and established Core Projects that would receive priority. The first of these was the "Global Description" project, which was meant to obtain data on the circulation of heat, fresh water and chemicals, as well as the statistics ofeddies. The second project—"Southern Ocean"—placed particular emphasis on studying theAntarctic Circumpolar Current and theSouthern Ocean’s interaction with the World Ocean. The third and final Core Project serving goal one was the "Gyre Dynamics Experiment." The second and third of these focuses are designed specifically to address the ocean’s role in decadal climate changes. Initial planning of the WOCE states that achievement of Goal 1 would involve "strong interaction between modeling and field activities," which are described further below.
2. Find the representativeness of the dataset for long-term behavior and find methods for determining long-term changes inocean currentsSpecifically:
Determine representative of specific WOCE data sets
Identify those oceanographic parameters, indices and fields that are essential for continuing measurements in a climate observing system on decadal time scales
Develop cost effective techniques suitable for deployment in an ongoing climate observing system[3]
Models in WOCE were used for both experimental design and data analysis. Models with use of data can incorporate various properties, including thermal wind balance, maintenance of thebarotropicvorticity budget, and conservation of heat, fresh water, or mass. Measurements useful for these parameters are heat, fresh water or tracer concentration; current, surface fluxes of heat and fresh water; sea surface elevation.[3]
Both inverse modeling and data assimilation were employed during WOCE. Inverse modeling is the fitting of data using a numerical least squares or maximum likelihood fitting procedure. The data assimilation technique requires data to be compared with an initial integration of a model. The model is then progressed in time using new data and repeating the process.[3]
The success of these methods requires sufficient data to fully constrain the model, hence the need for a comprehensive field program.
Goals for the WOCE Field Program were as follows.[1]
The experiment will be global in nature and the major observational components will be deployed in all oceans.
The requirement of simultaneity of measurements will be imposed only where essential.
The flexibility inherent in the existing arrangements for cooperative research in the worldwide oceanographic (and meteorological) community will be exploited as far as possible.
plans built around the availability ofERS–1 and ERS–2 (European),TOPEX/POSEIDON (US/French) to study fields of surface forcing and oceanic surface topography[2]
using chemical information (such asradioactive decay and atmospheric history) of passive compounds to study the formation rates and transport of water masses on climatological timescales
Ocean Surface Fluxes
using in-situ and satellite measurements to quantify fluxes of heat, water andmomentum (necessary for modelingthermohaline and wind-driven circulation)
Satellite Winds
using surface buoys, Voluntary Observing Ships (VOS) and satellite microwavescatterometer systems to measure the surface wind field
Surface Meteorological Observations from VOS
improvement of sampling and accuracy in surface meteorological measurements, as well increasing area coverage
Upper Ocean Observations from Merchant Ships-of-Opportunity
Ocean Circulation and Climate, Observing and Modelling the Global Ocean, 1st Edition, Eds.Gerold Siedler, John Gould & John Church, Academic Press, 736pp. (International Geophysics Series 77) 2001
Ganachaud, Alexandre (2003). "Large-scale mass transports, water mass formation, and diffusivities estimated from World Ocean Circulation Experiment (WOCE) hydrographic data".Journal of Geophysical Research: Oceans.108 (C7): 3213.Bibcode:2003JGRC..108.3213G.doi:10.1029/2002JC001565.
Revisiting the South Pacific subtropical circulation: A synthesis of World Ocean Circulation Experiment observations along 32°S, S. E. Wijffels, J. M. Toole, R. Davis, Journal of Geophysical Research, September 2012
WOCE observations 1990–1998; a summary of the WOCE global data resource, WOCE International Project Office, WOCE Report No. 179/02., Southampton, UK.(pdf 18.9 MB)
